package com.xyz.readWriteLock;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

class MyCache{
    private volatile Map<String,Object> map = new HashMap<>();
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    public void  put(String key,Object value){
        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"\t======开始写入:"+key);
            try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); }
            map.put(key,value);
            System.out.println(Thread.currentThread().getName()+"\t------写入完成");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.writeLock().unlock();
        }
    }
    public void  get(String key){

        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"\t开始读取:");
            try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); }
            Object result= map.get(key);
            System.out.println(Thread.currentThread().getName()+"\t读取完成"+result);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.readLock().unlock();
        }


    }
}

/**
 * @author 肖咉卓
 *
 * ReadWriteLock 读写锁
 * 多个线程同时读一。 个资源类没有任何问题，所以为了满足并发量，读取共享资源应该可以同时进行。
 *但是
 * 如果有一-个线程想去写共享资源来，就不应该再有其它线程可以对该资源进行读或写
 * 小总结：
 *      读-读能共存
 *      渎-写不能共存
 *      写-写不能共存
 */
public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCache myCache = new MyCache();
        for (int i=1;i <= 5;i++){
            final int tempInt=i;
            new Thread(() ->{
                myCache.put(tempInt+"",tempInt+"");
            },String.valueOf(i)).start();
        }
        for (int i=1;i <= 5;i++){
            final int tempInt=i;
            new Thread(() ->{
                myCache.get(tempInt+"");
            },String.valueOf(i)).start();
        }
    }
}
